Astigmatism and going about in a blur

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Andrew Chew - 22 Mar 2005 17:00 GMT

I have myopia at -2.25(left eye) and -2.75(right eye). The right eye also
has slight astigmatism at -0.50. Will going about without glasses cause the
astigmatism to worsen?

Also what do you think of the following article from New Scientist. It seems
to imply going about in a blur will lead to myopia deteriorating.

http://www.newscientist.com/article.ns?id=dn3082

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Jan - 22 Mar 2005 17:33 GMT

>I have myopia at -2.25(left eye) and -2.75(right eye). The right eye also
>has slight astigmatism at -0.50. Will going about without glasses cause the
>astigmatism to worsen?

No.

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Jan (normally Dutch spoken)

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Andrew Chew - 22 Mar 2005 18:22 GMT

>>I have myopia at -2.25(left eye) and -2.75(right eye). The right eye also
>>has slight astigmatism at -0.50. Will going about without glasses cause
>>the astigmatism to worsen?
>
> No.

Any thoughts on the New Scientist article?

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Mike Tyner - 22 Mar 2005 20:36 GMT

>I have myopia at -2.25(left eye) and -2.75(right eye). The right eye also
>has slight astigmatism at -0.50. Will going about without glasses cause the
>astigmatism to worsen?

No. Gradual, long-term changes in astigmatism happen whether you wear
glasses or not.

Myopia and astigmatism have different natural histories, but neither seems
to respond much to glasses. In infants, maybe, but nobody puts glasses on
infants without very good reasons.

> Also what do you think of the following article from New Scientist. It
> seems to imply going about in a blur will lead to myopia deteriorating.
> http://www.newscientist.com/article.ns?id=dn3082

There are lots of similar studies. Most of them were designed to prove that
removing glasses or lessening the correction would be *beneficial.* None of
them show the final degree of myopia is much different with full correction,
undercorrection, or no correction.

Regarding myopia, Parssinen found undercorrection made "no difference" in
one eye and was _detrimental_ in the other. If we assume that each subject
experienced the same environmental stimuli for the left and right eyes, it
just seems to be statistical error.

The same statistical variance caused the Malaysian study you cited to be
halted, because that's protocol. But we don't seriously believe
undercorrection is harmful.

Statistical variance and sampling errors are facts of life. That's why it's
difficult for one single study to establish "scientific truth". You have to
see findings replicated, and compare one technique with another. Notice that
the Malaysian study did not measure myopia.

-MT, OD

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